1. Field of the Invention
The invention relates to a multipart dowel for a removable anchor with an anchor pin which can be repeatedly pushed in and released.
2. The Prior Art
Anchors for board linings, which are undetachably inserted in brickwork by means of dowels, are known from DE 39 16 818. Said anchors carry thickenings and with the latter press a driving sleeve against the wall of the borehole in the brickwork. Saw teeth or lamellae disposed against the pulling direction prevent the anchor from being pulled from the borehole.
Furthermore, an anchor bolt with spreading wedges is described in DE 37 14 008. In the present case, the anchor bolt is enveloped by a spreading wedge. When the anchor bolt is pushed in the borehole, the spreading wedge is pressed spreaded against the wall of the borehole. An unreleasable connection is produced in this case as well. The same applies to a spreading anchor according to DE 43 24 244, which is made of metal. In this case, a conical anchor head presses a spreading tube against the wall of the borehole.
Multi-component dowels are known as well. DE 43 10 796 describes a spreading anchor which is enveloped by at least two spreading tubes, which are plugged one into the other. When the anchor is axially pulled, the spreading sleeves are spread radially for anchoring the anchor. Metal or plastic dowels are known from DE 30 36 627 and DE 27 11 845, which consist of a dowel sleeve and a dowel, whereby the dowel sleeve has a plurality of inclined scales, tongues and bridges on the outer side, which permit insertion of the dowel into the boreholes in the axial direction and wedge themselves against said direction. All of said dowels are intended to unreleasable retain anchor bolts in the underground.
Adjustable and releasable dowels are equipped with a thread. For example, an adjustable spreading dowel is known from DE 34 31 905, which consists of a dowel sleeve and a spreading body, whereby on the outer jacket surface of the spreading body, a thread located on the innter jacket surface of the dowel sleeve cooperates with the jacket surface of the spreading body. For removing the anchor bolt, CH-P 30 26 54 makes provision for a screw connection between an anchor, threaded jaws and a dowel sleeve, into which the anchor provided with a thread is pushed between the threaded jaws and spreads the latter, so that the threads will not interfere. When subjected to pulling load, the wedge surfaces of the threaded jaws and the threads get wedged and retain the anchor. The anchor can be removed from the dowel by turning it, screwing it out of the latter.
A removable two-component anchor-setting dowel for anchor pins has already been proposed, which is pushed into a borehole and secures the anchor pin by wedging against unintended loosening (DE 195 43 214). At least one groove with slanted flanks forming oblique planes pointing away from the opening of the borehole, and forming a parellelogram viewed in the cross section, is located in the inner wall of the outer dowel sleeve lining the borehole. A dowel-setting ring is fitted in the interior of the dowel sleeve, leaving a free space, said dowel-setting ring carrying on its outer jacket at least one ring forming in the cross section a parallelogram with slanted side surfaces corresponding with the flanks of the groove, and engaging the groove, partially filling the latter. The inner wall of the dowel setting ring carries zones of higher pressure and greater friction at least within the region of the ring or rings. For installing the anchor-setting dowel, the dowel sleeve is slotted lengthwise. It may be open also at the bottom, so that the dowel-setting ring without collar is pushed into the dowel sleeve from the bottom and the collar is then secured on the dowel-setting ring after it has been pushed in. Also, the dowel sleeve can be cut from a web and wound around the dowel-setting ring. Said dowels can be used only after they have been completely assembled. Replacement of the dowel-setting ring--which is subjected to wear--in the anchored dowel sleeve is not possible.